What moves Theme forward is the Thematic Argument. Why an argument? Because unless the audience shares the author's bias on the story's issues, it will not accept a blanket statement the author's proposed way of dealing with a particular problem is the best. The audience does want to be convinced--it wants to learn something useful in real life while being entertained at the same time. But, unless an author can successfully make an emotional argument supporting his bias through his Theme, he will not be able to change the heart of his audience.